The central nervous system plays a critical role in the control of the urinary bladder and autonomic neural circuits regulate the bladder at the level of spinal cord. Those complex networks enable conscious awareness of bladder filing and voluntary and involuntary control over the micturition.
Urinary tract function consists of storage and voiding functions. During the storage phase, the bladder detrusor muscle relaxes and urethral sphincter muscle contracts to maintain continence. When the bladder becomes full and the situation is considered as socially acceptable, the voiding occurs. During voiding phase, the bladder sphincters relaxes and the detrusor muscle contracts, permitting micturition. The mechanistic control of the bladder detrusor muscle and sphincters occurs through the activity of autonomic and somatic networks in the spinal cord, which communicate reciprocally with supraspinal centers.
Parasympathetic nerves trigger the bladder contraction during voiding via the pelvic plexus. Sympathetic neurons have the effect of maintaining bladder relaxation, and travel along the iliohypogastric nerve. Somatic cholinergic nerves arising in Onuf’s nucleus travel in the pudendal nerve to regulate the external urethral sphincter.
Hou et al. used optogenetic techniques to identify a population of corticotrophin-releasing hormone (CRH) positive neurons within the mouse Barrington’s nucleus whose activity correlated with bladder contractions (Hou X, et al. Cell 2016). These neurons were found to send glutamatergic projections to the spinal cord. To investigate the mechanisms underlying the bladder control by Barrington’s nucleus, we recorded the neural activity of Barrington’s nucleus and analyzed those activity associated with mice micturition cycle. Barrington’s nucleus neural activity facilitated voiding and also small contraction of the bladder during micturition cycle indicating that Barrington’s nucleus seemingly controls the voiding but also storage function. Furthermore, investigation of Barrington’s nucleus will uncover the pathological etiology of bladder dysfunction associated with central nervous system.